The present invention relates to packaging films, and more particularly to a method of increasing the gas transmission rate of a packaging film.
It is sometimes useful to package a product within a packaging atmosphere that is different from the composition (e.g., oxygen content) and/or condition (e.g., pressure) of ambient air. For example, fresh red meat may be packaged within a modified atmosphere to extend the shelf life of the packaged fresh red meat. The modified atmosphere may be one having a low amount of oxygen, such as less than about 0.5 volume % oxygen or less than about 0.05 volume % oxygen.
However, fresh red meat packaged in a low-oxygen atmosphere typically has a purple color that may displease retail customers. Therefore, it may be desirable to allow the composition and/or conditions of the modified atmosphere within the package to approach that of ambient air after the package arrives at a supermarket or other retail outlet. For example, oxygen from ambient air may be allowed to reach the interior of the package in order to cause the meat to “bloom” to a red color suitable for retail display.
Several package designs provide for transportation of a food product in a low-oxygen environment, and for the quick introduction of oxygen to allow the food product to bloom at the retail outlet before display to the consumer. See, for example, U.S. Pat. Nos. 5,591,468; 5,686,126; 5,779,050; 5,919,547; and 6,032,800; each of which is incorporated herein in its entirety by reference.
Such packages may include a peelable laminate, for example a laminate that may be separated (e.g., hand peeled) into a relatively oxygen-permeable film and a relatively oxygen-impermeable film. Such a laminate may be sealed to a support member—such as a tray supporting a fresh red meat product—to form a low-oxygen modified-atmosphere, closed package having a relatively low oxygen-transmission rate to maintain the internal modified atmosphere in its modified condition. At the retail outlet, the relatively oxygen-impermeable film may be peeled from the laminate leaving the relatively oxygen-permeable film sealed to the tray—resulting in a closed package having a relatively high oxygen transmission rate through the film, so that oxygen relatively quickly transfers through the film to bloom the meat to a bright red. However, a drawback to such systems is the requirement for peeling the relatively oxygen-impermeable film from the laminate.